Dapr 客户端 搭配 WebApiClientCore 玩耍服务调用

使用Dapr 客户端 处理服务调用，需要遵循的他的模式，通常代码是这个样子的：

var client = DaprClient.CreateInvokeHttpClient(appId: "routing");
var response = await client.GetAsJsonAsync($"/accounts/{17}", cancellationToken);
var account = await response.Content.ReadFromJsonAsync<Account>(cancellationToken: cancellationToken);

我更希望是这样子调用:

public interface IBank { [HttpGet("/accounts/{accountId}")] Task<Account> GetUser(string accountId, CancellationToken cancellationToken = default);

[HttpPost("/deposit")] Task<Account> Deposit([JsonContent] Transaction transaction, CancellationToken cancellationToken = default);

[HttpPost("/withdraw")] [RawReturn(Enable =true, EnsureSuccessStatusCode = false)] Task<HttpResponseMessage> Withdraw([JsonContent] Transaction transaction, CancellationToken cancellationToken = default); }

var account = await bankClient.GetUser("17", cancellationToken);

我们可以用 Refit，RestEase 或者是 WebApiClientCore 来达到这样的效果， 那么在Dapr 里面使用这些库如何做到呢， 在Dapr的客户端库里面有一个Handler 的官方实现：InvocationHandler。 搭配这个InvocationHandler 就可以和这几个库，在本文中，我们重点介绍Dapr Client 如何搭配 WebApiClientCore。

public interface IBank

{ [HttpGet("/accounts/{accountId}")] Task<Account> GetUser(string accountId, CancellationToken cancellationToken = default);

[HttpPost("/deposit")] Task<Account> Deposit([JsonContent] Transaction transaction, CancellationToken cancellationToken = default);

[HttpPost("/withdraw")] [RawReturn(Enable =true, EnsureSuccessStatusCode = false)] Task<HttpResponseMessage> Withdraw([JsonContent] Transaction transaction, CancellationToken cancellationToken = default); }

public class WebapiClientExample : Example { public override string DisplayName => "WebapiClient";

private IBank bankClient;

public WebapiClientExample(IBank bank) { bankClient = bank; }

public override async Task RunAsync(CancellationToken cancellationToken) { var options = new JsonSerializerOptions(JsonSerializerDefaults.Web);

// Scenario 1: Check if the account already exists. Account? account = null; try { account = await bankClient.GetUser("17", cancellationToken); } catch (ApiException ex) { // Account does not exist. }

Console.WriteLine($"Scenario 1: account '17' {(account is null ? "does not exist" : "already exists")}");

// Scenario 2: Deposit some money var transaction = new Transaction() { Amount = 100m, Id = "17", };

// read updated balance account = await bankClient.Deposit(transaction, cancellationToken); Console.WriteLine($"Scenario 2: account '17' has '{account?.Balance}' money");

// Scenario 3: Handle a validation error without exceptions transaction = new Transaction() { Amount = 1_000_000m, Id = "17", }; HttpResponseMessage response = null;

response = await bankClient.Withdraw(transaction, cancellationToken); if (response.StatusCode != HttpStatusCode.BadRequest) { // We don't actually expect this example to succeed - we expect a 400 Console.WriteLine("Something went wrong :("); return; } var problem = await response.Content.ReadFromJsonAsync<ProblemDetails>(cancellationToken: cancellationToken); Console.WriteLine(

var services = new ServiceCollection(); services.AddTransient<Example, WebapiClientExample>(); services.AddLogging();

services .AddScoped<InvocationHandler>() .AddHttpApi<WebapiClientExample.IBank>(o => o.HttpHost = new Uri("http://bank")) .AddHttpMessageHandler<InvocationHandler>(); var serviceprovider = services.BuildServiceProvider();

代码的核心部分就在于上面红色的部分，我们把InvocationHandler 加入到AddHttpApi ，就可以和 dapr 一起玩耍了。